JPH07167992A - Quantity reducing method of radioactive contaminated water produced by decontamination of radioactive contaminant, and quantity reducing device - Google Patents

Abstract

PURPOSE:To enable the repeated use of water used for decontamination and reduce the quantity of radioactive contaminated water discharged outside by flocculating contaminant in aqueous decontaminating liquid by a flocculant, and filtering flocculated material. CONSTITUTION:Radioactive contaminant 1 is washed with a chelate solution 10 in a decontaminating tank 22 using an ultrasonic vibrating device 21. The aqueous decontaminating liquid 2 is transferred to a flocculating device 14 and subjected to pH adjustment, and alkali is added thereto. A flocculant is then added from one flocculant feeder 15, and a highmolecular flocculant is fed from the other feeder 15 during agitation by an agitating device 29. Flocculated material 5 is thus formed and separated into floc 30 and sludge 31. The flocculated material 5 is then fed together with the decontaminating liquid 2 to a filter device 17 through a valve 28 and filtered by filter material 32 so as to be separated into the flocculated material 5 and clear water 6. The clear water 6 is inspected by a pH meter 34 and a conductivity meter 35, and the presence of Fe ion is judged. In the case of being in a specified range, the clear water 6 is fed to a feeder 19 for the decontaminating liquid 2 through a communicating passage 36 and a pump 37.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for reducing the amount of radioactive polluted water produced by decontamination of radioactive pollutants used in nuclear power plants and the like.

[0002]

The inventor of the present invention previously invented a method for decontaminating radioactive contaminants with methylene chloride,
A patent application was filed (Japanese Patent Application No. 3-68862). Since the present invention relates to an improvement of the above-mentioned applied invention and is also used for decontamination of other radioactivity, the above-mentioned applied invention will be described first. The method of the present invention, as described above,
The method is not limited to the above disclosed invention, and it is needless to say that the method is also applied to radioactive contaminated water generated by decontamination of radioactive pollutants by a method using another aqueous decontamination solution.

The disclosed invention discloses radioactive pollutants (generally, the above-mentioned pollutants generated in a nuclear power plant are various devices,
Equipment and the like, which are usually coated with epoxy resin in many cases. ) Is first dipped in a methylene chloride solution to swell the coating, etc., and is sprayed with a methylene chloride solution for cleaning, is dissolved and peeled off, and the methylene chloride solution used for this cleaning is filtered and then distilled. The methylene chloride solution itself is decontaminated, and the decontaminated methylene chloride is used for cleaning the radioactive contaminants.

On the other hand, the radioactive substance washed with methylene chloride as described above is almost decontaminated by the washing. However, since this decontamination alone cannot completely decontaminate, the next step is to wash the washed contaminants with a chelate aqueous solution and by applying ultrasonic vibration. In this way, the pollutant was almost completely decontaminated, and when it was rinsed with fresh water and its radioactivity was measured with a Geiger counter, it was almost 2000 CPM at first.
Radioactivity that was (Count Per Minute) is 0 CPM
It was.

[0005]

However, it has been found that the above invention still has the following problems. In the above invention, the radioactive contaminants are washed with the chelate aqueous solution as described above, and this aqueous solution is already contaminated by the radioactivity due to the above washing. A large amount of this contaminated water is generated and packed in drums or the like and stored in waste poles or the like, which requires a huge space.

In order to avoid the use of this huge space, the radioactive polluted water is treated with an ion exchange resin. Then, the radioactivity of the polluted water is transferred to the ion exchange resin, and the water is fresh water. However, instead of this, a large amount of ion-exchange resin contaminated with radioactivity is generated, and this is packed in a drum and stored in the waste mines, etc. Therefore, it is unavoidable that a huge space is required. Regarding such a situation, the radioactivity of the object is not limited to the case where the radioactive pollutant is washed with the chelate aqueous solution described above, but generally an aqueous decontamination solution such as water or a solution composed of water and other substances is used. In the case of decontamination, for example, in the case of electro-deletion dyeing, etc., it is an inevitable problem.

The above water-based decontamination solution can be decontaminated by distillation. However, in such a case, water has a large latent heat of vaporization and consumes a large amount of power, resulting in a huge expense. The present invention has been made to solve such a problem,
The purpose is to reduce the amount of radioactive pollutant used to decontaminate radioactive pollutants using water or a water-based decontamination solution such as a solution consisting of water and other substances, and It is to provide a weight loss device.

[0008]

With respect to the present invention which achieves the above-mentioned object, a method will be first described in which a radioactive contaminant 1 is treated with an aqueous decontamination solution 2 such as water or a solution consisting of water and other substances. The decontamination was performed, and the flocculant 3 was added to the water-based decontamination solution 2 used for this decontamination to cause the pollutants 4 to agglomerate 5. The agglomerates 5 were filtered, and the fresh water 6 generated by the filtration was used to A method for reducing radioactively contaminated water produced by decontamination of radioactive pollutants, which comprises forming an aqueous decontamination solution 2 and using the aqueous decontamination solution 2 for decontamination of radioactive pollutants 1. Further, the purified water 6 generated by the above filtration is further purified by a purifying device 7, the purified water 8 generated by the purification is used to form the water-based decontamination solution 2, and the water-based decontamination solution 2 is converted into a radioactive contaminant 1. A method for reducing the amount of radioactively contaminated water produced by decontaminating the radioactive contaminants, which is used for decontamination.

The water-based decontamination solution 2 is a method for reducing the amount of radioactively contaminated water produced by decontaminating the radioactive contaminants, which is the chelating solution 10 containing a chelating agent. The water-based decontamination solution 2 is a method for reducing the amount of radioactively contaminated water produced by decontaminating the radioactive contaminants that are the electrolyte solution 11.

[Action]

Next, the apparatus of the present invention will be described. It is a decontamination apparatus 1 for decontaminating radioactive contaminants 1 with an aqueous decontamination solution 2 such as water or a solution consisting of water and other substances.
3; an aggregating device 14 provided after the decontaminating device 13 for aggregating the contaminants 4 in the aqueous decontaminating solution 2; the aggregating device 1 including an aggregating agent supply device 15 and an aggregating tank 16.
4; Filtration device 17 provided after the aggregating device 14;
Reduction of radioactive polluted water caused by decontamination of radioactive pollutants, characterized by comprising a supply device 19 for the water-based decontamination liquid 2 provided after the filtering device 17 and before the decontamination device 13. It is a device. Further, a purifying device 7 provided in the latter stage of the filtering device 17 for purifying the fresh water 6 generated by the filtration of the filtering device 17;
A device for reducing radioactive contaminated water produced by decontamination of the radioactive contaminants, characterized in that it comprises a supply device 19 for the water-based decontamination liquid 2 provided in the preceding stage of the decontamination device 13. Further, the decontamination device 13 is the ultrasonic vibration device 2
1 is a decontamination tank 22 that contains a chelate solution 10 as an aqueous decontamination solution 2 and is a device for reducing radioactive contaminated water generated by decontamination of the radioactive contamination. Further, the decontamination device 13 is an electrolytic device 23, and the water-based decontamination liquid 2 is an electrolytic solution 11.
The apparatus for reducing the amount of radioactive contaminants produced by decontamination of the radioactive contaminants.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 is a radioactive contaminant, which is contained in a decontamination device 13. And this decontamination device 13
As an example, the decontamination tank 22 stores the chelate solution 10 as the water-based decontamination solution 2 and is vibrated by the ultrasonic vibration device 21. In addition, the chelate solution 10 has an inlet 2
5, it is circulated by the outlet 26.
Incidentally, 27 is a flow-down passage, and 28 is a valve. Next, 14 is an aggregating device, which comprises an aggregating agent supply device 15, an aggregating tank 16, and an agitating device 29 as an example. Although two coagulant supply devices 15 are shown, one supplies a polymer coagulant and the other supplies an inorganic coagulant. In the present invention, the coagulant is also referred to as a coagulant. Since it has almost the same action, it is treated as a flocculant.
That is, in the present invention, the aggregating agent refers to all the agents which cause aggregation or coagulation of the pollutant 4 in the aqueous decontamination liquid 2.

The aggregate 5 is separated into a frog 30 and a sludge 31. Next, 17 is a filtering device, and the filtering material 32
And a filter tank 33. 34 is a PH meter, 35
Indicates a conductivity meter. 6 shows fresh water generated by filtration.
Further, 36 is a communication pipe, 37 is a pump, 19 is a supply device of the above-mentioned water-based decontamination solution, and comprises a tank 38, a pump 39, a decontamination agent supply device 40 and the like. The decontaminating agent supplying device 40 is a chelating agent supplying device as an example in this case. However, when the water-based decontamination solution 2 is an electrolytic solution, unlike this, it can be changed to an acid or alkali agent or salt supply device. Next, 7 is a refining device, 41 is a housing, 4
Reference numeral 2 denotes a stainless-steel cylindrical casing having a hole, in which activated carbon 43 is accommodated, and a nylon string or cotton string 44 is wound around the outer periphery of the casing 42. 45 is a tank, 46 is an adsorption layer made of ion exchange resin, 47 is a second tank, 48
Indicates a pump. The operation of the above-described apparatus will be described. First, the radioactive contaminant 1 is removed from the decontamination tank 22.
After being decontaminated, the water-based decontamination liquid 2 is washed with the chelating liquid 10 and by using the ultrasonic vibration device 21.
Moved to 4. Then, pH adjustment was first performed, alkali addition was performed, and the liquid (addition device not shown) was made alkaline. Next, aluminum sulfate as a liquid electrolyte is added as a coagulant from one coagulant supply device 15 and stirred by a stirrer 29. During this stirring, a polymer coagulant from the other coagulant supply device 15, for example, A polyacrylamide polymer flocculant was supplied. Then, agglomeration and precipitation occur, and agglomerates 5 are produced. The aggregate 5 is separated into a frog 30 and a sludge 31. Next, the agglomerate 5 opens the valve 28, is supplied to the filtration device 17 with the water-based decontamination liquid 2, is filtered by the filter medium 32, and is separated into the agglomerate 5 and the fresh water 6. Then, the fresh water 6 is inspected by the PH meter 34 and the conductivity meter 35 to determine the presence of Fe ions, and if it is within a predetermined range, from the communication passage 36,
A pump 37 feeds the water-based decontamination liquid 2 to a supply device 19, where a chelating agent is supplied from a decontamination agent supply device 40, and is supplied to the decontamination device 13 by a pump 39.

When the Fe ions in the fresh water 6 are more than a predetermined range, they are sent to the purifying device 7 in the next stage, adsorbed and purified by the activated carbon 43, and sent to the supplying device 19. When the water is finally taken out, it is passed through the ion exchange resin layer 46. Further, the above refining device 7
Is not limited to the one using activated carbon, and any kind of device can be used as long as it can be purified.

Next, FIG. 2 shows another embodiment of the present invention in which the decontamination device 13 is formed in substantially the same manner except that it is different. The decontamination device 13 in FIG. 2 is an electrolysis device. In the figure, 50 is an anode, 51 is a cathode,
1 is a radioactive pollutant made of metal. The water-based decontamination solution 2 is an electrolytic solution in this case, and an aqueous solution of sodium chloride was used as an example.

After the decontamination by electrolysis is performed in the decontamination apparatus 13 shown in the same figure, the electrolytic solution is repeatedly circulated through the steps substantially the same as the steps shown in FIG. The decontamination apparatus 13 is treated in the same manner thereafter, such as when high-pressure injection of external water for electrolysis and other washing with water or an aqueous solution of acid or alkali is performed, and the decontamination apparatus 13 is circulated as described above. It can be used repeatedly, and the discharge of polluted water to the outside can be greatly reduced.

Next, the conventional decontamination of the water-based decontamination liquid 2 itself has the following problems. This is because the packing between the container, the apparatus, the pipes, etc. for containing the water-based decontamination liquid 2 causes α-rays and β-rays generated by the water-based decontamination liquid 2 and the like.
That is, the elasticity is lost with respect to γ rays and the like. Also, there was a small amount of packing that was not affected by the methylene chloride adhering to the radioactive contaminant 1. Therefore, the inventor of the present invention solves this problem by using a special packing that can solve the above problems and providing it between the above-mentioned containers, devices and piping. Regarding this special packing, it is a packing formed of perfluoroelastomer, which is manufactured and sold by DuPont, USA and is called Kalrez under the trade name. By using the packing made of this perfluoroelastomer and for the valve of the pump or the like, water or the water-based decontamination liquid 2 itself can be decontaminated, and methylene chloride can also be used, which is excellent. The decontamination method and equipment could be obtained.
1 and 2, reference numeral 53 denotes packing made of the above perfluoroelastomer, and as shown in the drawing, the decontamination apparatus 1
3, the aggregating device 14, the filtering device 17, the supply device 19 of the water-based decontamination liquid 2, and the like, and the pipe 54. It is also provided between the electrolyzer and the pipe 54.

By forming the pipes in this way, the pipes 54 can be removed from various devices, and thus the insides of these devices and the pipes 54 can be easily decontaminated. And the above-mentioned perfluoroelastomer, against the α rays, β rays, γ rays generated by water or the water-based decontamination liquid 2,
The loss of elasticity is much less than that of general rubber, and it does not cause any problems after being used for a long time in practical use. In addition, it is practically unaffected by the methylene chloride.

[0018]

Industrial Applicability The present invention is constructed as described above, and the contaminants in the water-based decontamination solution are aggregated by the aggregating agent and filtered, so that the water used for decontamination can be repeatedly used, and therefore, the external It is possible to greatly reduce the amount of radioactive polluted water discharged.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention and schematically showing a device for reducing contaminated water generated by decontamination of radioactive contaminants.

FIG. 2 is a view corresponding to FIG. 1, showing another embodiment of the present invention.

[Explanation of symbols]

 1 Radioactive Pollutants 2 Aqueous Decontamination Solution 3 Flocculant 5 Flocculant 6 Clean Water 7 Purification Device 8 Purified Water 13 Decontamination Device 14 Flocculation Device 15 Flocculant Supply Device 19 Aqueous Decontamination Solution Supply Device

Claims (8)

[Claims] 1. A radioactive contaminant 1 is decontaminated with an aqueous decontamination solution 2 such as water or a solution consisting of water and another substance, and an aggregating agent 3 is added to the aqueous decontamination solution 2 used for this decontamination. To agglomerate the pollutant 4 and to filter the agglomerate 5. The clear water 6 generated by the filtration is used to form the water-based decontamination solution 2, and the water-based decontamination solution 2 is converted to the radioactive contaminant 1 A method for reducing the amount of radioactively contaminated water produced by decontamination of radioactive pollutants, which is used for decontamination of radioactive pollutants. 2. A radioactive contaminant 1 is decontaminated with an aqueous decontamination solution 2 such as water or a solution containing water and another substance, and the aggregating agent 3 is added to the aqueous decontamination solution 2 used for this decontamination. To agglomerate the pollutant 4 and to filter the agglomerate 5. The purified water 6 produced by the filtration is further purified by a purifier 7 and the water-based decontamination using the purified water 8 produced by the purification. Forms liquid 2,
A method for reducing radioactively contaminated water produced by decontamination of radioactive pollutants, characterized in that the aqueous decontamination solution 2 is used for decontamination of radioactive pollutants 1. 3. The method for reducing the amount of radioactively contaminated water produced by decontamination of radioactive contaminants according to claim 1, wherein the aqueous decontamination liquid 2 is a chelating liquid 10 containing a chelating agent. 4. The method for reducing the amount of radioactive polluted water produced by decontaminating radioactive contaminants according to claim 1 or 2, wherein the aqueous decontaminating solution 2 is an electrolytic solution 11. 5. A decontamination device 13 for decontaminating a radioactive pollutant 1 with an aqueous decontamination solution 2 such as water or a solution composed of water and another substance; provided at a subsequent stage of the decontamination device 13. Further, a flocculating device 14 for flocculating the pollutant 4 in the water-based decontamination liquid 2 using a flocculant 3; a flocculant supply device 15 and a flocculating tank 16
The aggregating device 14 comprising: a filtering device 17 provided after the aggregating device 14; the water-based decontamination liquid 2 provided after the filtering device 17 and before the decontamination device 13.
A device 19 for reducing the amount of radioactively contaminated water produced by decontamination of radioactive contaminants. 6. A decontamination apparatus 13 for decontaminating a radioactive contaminant 1 with an aqueous decontamination solution 2 such as water or a solution composed of water and another substance; provided at a subsequent stage of the decontamination apparatus 13. An aggregating device 14 for aggregating the contaminant 4 in the water-based decontamination liquid 2;
The aggregating device 14 including the aggregating agent supply device 15 and the aggregating tank 16; the filtering device 1 provided at the subsequent stage of the aggregating device 14.
7: The filtering device 1 provided at the subsequent stage of the filtering device 17.
A purification device 7 for purifying the fresh water 6 produced by the filtration of 7; and a supply device 19 for the water-based decontamination liquid 2 provided at the latter stage of the purification device 7 and before the decontamination device 13. A device for reducing the amount of radioactive polluted water produced by decontamination of radioactive pollutants. 7. The decontamination device has an ultrasonic vibration device 21,
The decontamination tank 22 containing the chelating solution 10 as the water-based decontamination solution 2, and the apparatus for reducing radioactive contaminated water produced by decontamination of radial contaminants according to claim 5 or 6. 8. The decontamination apparatus is an electrolytic apparatus, and the aqueous decontamination solution is an electrolytic solution. The apparatus for reducing the amount of radioactive polluted water produced by decontamination of radioactive pollutants according to claim 5 or 6.